Oil supply devices for supplying oil to respective parts of an internal combustion engine have been known in the art.
Patent Document 1 discloses a liquid-operated unit, which includes a high pressure chamber, an intermediate pressure chamber, and a low pressure chamber as a reservoir for a liquid pressure medium, and in which the low pressure chamber communicates with the intermediate pressure chamber through a diaphragm opening running through a partition wall between the low pressure chamber and the intermediate pressure chamber.
Meanwhile, a liquid-operated variable valve mechanism for controlling the activation of intake and exhaust valves of an engine (internal combustion engine) with a liquid medium has also been known in the art.
Patent Document 2 discloses a variable valve mechanism (corresponding to a liquid-operated variable valve mechanism), which includes a hydraulic unit having an internal oil passage filled with an oil functioning as a power transmission medium, in which the oil passage is interposed between a rotating cam and an exhaust valve or an intake valve, and which is able to freely control the opening/closing timing and degree of the valve by opening and closing a solenoid valve provided for the oil passage to increase and decrease the flow rate of the oil flowing through the oil passage.